1. Technical Field
The present invention relates to a cord bushing, and more specifically relates to a cord bushing having a structure which prevents the same from unintentional falling off while it is detached for the purpose of maintenance or the like.
2. Background Art
In general, when an electrical cord is laid through a case or outer panel of an electrical apparatus for electrical connection with an interior connecting terminal, a cord bushing is used to hold the cord and then to be fitted into an aperture formed in the case for protection of the cord. As the cord is securely held by the resilient cord bushing made of such as a synthetic resin, there is no fear that, when the cord is pulled, the force is directly applied to the interior connecting terminal and the cord is almost free from breakage or other troubles even when it suffers repeated bending at a fixed location.
Such a cord bushing includes a body having at one end thereof a flange which cooperates with locking means to lock the cord bushing to the case or the like, when the body is inserted into the aperture from outside of the case. As the flange covers the aperture and the locking means is hidden inside of the case, a neat finish can be obtained.
Such a cord bushing is, in normal use, securely anchored to the case or the like by the locking means, but when any trouble is found in the electrical apparatus, it is sometimes required to detach the cord bushing for maintenance. Such cases are, for example, when the cord itself is to be changed because of broken wires and when locking of the cord is to be released to remove any electronic component inside of the apparatus to which the cord is directly connected.
Such maintenance is often carried out at the location where the electrical apparatus is installed, such as the home of a general consumer or a workshop. There is a risk that the cord bushing removed for repair or maintenance can fall off and become lost. And moreover, in the field, such as at a home or workshop it is sometimes difficult to get spare cord bushings, so once the cord bushing is lost, it is supposed that maintenance can not be finished. The repairman who has lost a cord bushing may carry out assembly without the cord bushing under the necessity of temporary use of the electrical apparatus, but such an apparatus may lack safety and reliability. Therefore, it has been strongly desired to provide a device for preventing the falling off of a component which will be possibly removed during maintenance. The importance will be understood from the fact that in some countries in Europe and America provision of such a device is required.
A cord bushing including falling-off preventing means has been proposed, as disclosed in U.S. Pat. No. 3,779,494 which discloses a cord bushing employing an anchor-like locking member having its cross-sectional size substantially larger than the size of the cord bushing fitting aperture. But there is a disadvantage that such a large locking member may become an obstacle in the interior of the electrical apparatus. Other various devices have been proposed, but they cannot be said to be satisfactory for the reason such as that a cord bushing holding a cord is difficult to be removed or that the appearance of a cord bushing becomes defective.